python - 从系列中删除分钟和小时

Question

早上好

我有以下数据框(年、月、日、小时、秒):

print(df)

     Date               Price
2018-01-02 09:42:00       2
2018-01-02 09:46:00       4
2018-01-02 10:22:00       6
...

我想得到，没有分秒:

print(final_df)

     Date               Price
2018-01-02                2
2018-01-02                4
2018-01-02                6
...

我试过:

df['Date'] = datetime.datetime.strptime(df['Date'], '%Y-%m-%d').date()

但它报告“strptime() argument 1 must be str, not Series”

Answer 1

如果不是日期时间列需要to_datetime与 dt.date :

print (df.dtypes)
Date     object
Price     int64
dtype: object

df['Date'] = pd.to_datetime(df['Date']).dt.date

print (df.dtypes)
Date     object
Price     int64
dtype: object

print (df['Date'].head().apply(type))
0    <class 'datetime.date'>
1    <class 'datetime.date'>
2    <class 'datetime.date'>
Name: Date, dtype: object

或者，如果需要没有小时、分钟和秒的日期时间，请使用dt.floor :

df['Date'] = pd.to_datetime(df['Date']).dt.floor('d')

print (df.dtypes)
Date     datetime64[ns]
Price             int64
dtype: object

print (df['Date'].head().apply(type))
0    <class 'pandas._libs.tslibs.timestamps.Timesta...
1    <class 'pandas._libs.tslibs.timestamps.Timesta...
2    <class 'pandas._libs.tslibs.timestamps.Timesta...
Name: Date, dtype: object

---

如果日期时间列:

print (df.dtypes)
Date     datetime64[ns]
Price             int64
dtype: object


df['Date'] = df['Date'].dt.date

df['Date'] = df['Date'].dt.floor('d')